Setting valve depth/height?

"Sinking" valves through excessive cutting and/or multiple valve jobs normally hurts flow. Otherwise, same as brian6pac said.

Best angles, widths, # of angles. etc. is normally determined by the flow characteristics of each type of head, the intended use, cam, rpm and experience of the machinist.

Trying to get everything the same AND best/correct is good for performance. "Blueprinting" - not necessarily to OEM factory specs.